refrigerator started tripping gfi

[mtnelectrical]

A refrigerator was working fine connected to a gfi receptacle for over a year, but yesterday morning started tripping the gfi. I went there and without checking anything I replaced the gfi. For my surprise, the problem remained. I thought the problem is the refrigerator but Iconnected to another gfi in the kitchen and there was no problem. The compressor motor runs at less than 2 amps. Any ideas?

 

[texie]

A refrigerator was working fine connected to a gfi receptacle for over a year, but yesterday morning started tripping the gfi. I went there and without checking anything I replaced the gfi. For my surprise, the problem remained. I thought the problem is the refrigerator but Iconnected to another gfi in the kitchen and there was no problem. The compressor motor runs at less than 2 amps. Any ideas?

Possibly has partial leakage to ground that is right on the edge and given the 4-6 ma tolerance of the GFCI that could explain it. Or maybe it only occurs when the frig is doing something such as in defrost mode.
I think we are going to see a lot more of this with more friges on GFCI under the 2014 NEC.

 

[mtnelectrical]

The weird thing is that I have tried on a different gfi and does not Tripp it

 

[petersonra]

The weird thing is that I have tried on a different gfi and does not Tripp it

different GFCIs trip at slightly different points. it is like with a circuit breaker. One 15A CB might stay on indefinitely at 20A while another trips.

you can test where a GFCI will trip by hooking up a resistor between line and ground at the outlet. anything over about 2800 Ohms should not cause a trip (that is about 4 mA). Anything under about 1900 Ohms should trip it (that is about 6 mA). 10 W resistors should work.

 

[mtnelectrical]

The weird thing is that I have tried on a different gfi and does not Tripp it

 

[K8MHZ]

The weird thing is that I have tried on a different gfi and does not Tripp it

Did you move it? If so, try using an extension cord to connect the fridge physically located where it doesn't trip to the GFCI that the fridge does make trip.

 

[don_resqcapt19]

Why did you replace the first GFCI? Did it trip when you pushed the test button?

A GFCI is not permitted to trip below 4mA, must trip above 6mA and may trip between 4 and 6mA. As others have said it could be just the differences in the trip points, or maybe the one that does not trip doesn't really work.

 

[xformer]

Why did you replace the first GFCI? Did it trip when you pushed the test button?

A GFCI is not permitted to trip below 4mA, must trip above 6mA and may trip between 4 and 6mA. As others have said it could be just the differences in the trip points, or maybe the one that does not trip doesn't really work.

Could GFCI for equipment be utilized in this situation?

 

[iwire]

Could GFCI for equipment be utilized in this situation?

GFCI is for people, GFP is for equipment.

If the area requires a GFCI you cannot replace it with GFP.

 

[Barbqranch]

Did you see it trip, or does it trip only when someone is touching a sink and reaches over to open the refer (or something like that). That is a memory from my childhood, beforefore GFCIs. Got a "nice" shock, turned the plug around, no more shock. Today I would replace the refer (except I was 8 at the time).

 

[fmtjfw]

If a GFCI starts tripping with an appliance plugged into it and you replace the GFCI and the tripping continues, you should assume the appliance is leaking too much current to ground from either the hot or neutral wires.

To verify this, if you care, you need to be able to read the difference in current between the hot and neutral wires passed the GFCI and feeding the appliance. If you separate the hot and neutral wires from the grounding wire in an extension cord and pass the hot and neutral only through a clamp-on ammeter that can display 4 milliAmps then you can look for excessive leakage.

The problem is finding such a beast.

Here is what I have done:
1) I made three separate coils of 10 turns each, black, white, and green, and taped them to hold their shape.
2) I connected one end of each coil to a plug and the other end to a receptacle, matching the colors.
3) the coils are side by side.


I can use a clamp on meter around the black and white coils to see the difference in the currents since when the current is flowing one way in the black coil it is flowing the opposite in the white coil. This difference is what the GFCI is looking for. I have multiplied the currents by 10 as far as the clamp-on knows and so have a chance of seeing milliamps with a meter I can afford.

Picture to follow in future post.

 

[mtnelectrical]

I changed it because gfi was tripping as soon as you plug the refri. Home owner run at extension cord to another receptacle protected by another gfi and it works there. I replaced the supposed defective gfi with a new one and it troops as soon as we plug the refri. I'm gonna test the other gfi. It might be defective and not tripping. I'll post what I find later

 

[K8MHZ]

If a GFCI starts tripping with an appliance plugged into it and you replace the GFCI and the tripping continues, you should assume the appliance is leaking too much current to ground from either the hot or neutral wires.

To verify this, if you care, you need to be able to read the difference in current between the hot and neutral wires passed the GFCI and feeding the appliance. If you separate the hot and neutral wires from the grounding wire in an extension cord and pass the hot and neutral only through a clamp-on ammeter that can display 4 milliAmps then you can look for excessive leakage.

The problem is finding such a beast.

Here is what I have done:
1) I made three separate coils of 10 turns each, black, white, and green, and taped them to hold their shape.
2) I connected one end of each coil to a plug and the other end to a receptacle, matching the colors.
3) the coils are side by side.


I can use a clamp on meter around the black and white coils to see the difference in the currents since when the current is flowing one way in the black coil it is flowing the opposite in the white coil. This difference is what the GFCI is looking for. I have multiplied the currents by 10 as far as the clamp-on knows and so have a chance of seeing milliamps with a meter I can afford.

Picture to follow in future post.

That's cool!

Thanks for sharing that with us.

 

[K8MHZ]

I changed it because gfi was tripping as soon as you plug the refri. Home owner run at extension cord to another receptacle protected by another gfi and it works there. I replaced the supposed defective gfi with a new one and it troops as soon as we plug the refri. I'm gonna test the other gfi. It might be defective and not tripping. I'll post what I find later

Have you tried using the extension cord on the gfci that trips?

 

[GoldDigger]

Have you tried using the extension cord on the gfci that trips?

Possibly the EGC in the extension cord is open?

 

[fmtjfw]

unless the fault is a leak to EGC

unless the fault is a leak to EGC

Possibly the EGC in the extension cord is open?

Unless a EGC is connected to the Neutral or Hot conductor on the load side of the GFCI (with a resistance that allows a total current of 4--6mA or more) it has no effect.

EGCs are not required for either the line or load sides of a GFCI. There are applications of GFCIs that require this independence.

The only harm from an absent EGC is the pushbutton plugin "GFCI testers" don't work.

 

[K8MHZ]

Possibly the EGC in the extension cord is open?

Just a step to eliminate the variables.

If frige does not trip any gfci using the extension cord, but consistently trips the gfci without one, it can be assumed that the extension cord is affecting the results.

If fridge does trip the gfci with the cord, it may be safe to say that it does not affect the results.

If the cord does not affect the results, I would suspect the fridge to be the culprit and take some measurements. I would also suspect the gfci is working properly.

 

[K8MHZ]

Unless a EGC is connected to the Neutral or Hot conductor on the load side of the GFCI (with a resistance that allows a total current of 4--6mA or more) it has no effect.

EGCs are not required for either the line or load sides of a GFCI. There are applications of GFCIs that require this independence.

The only harm from an absent EGC is the pushbutton plugin "GFCI testers" don't work.

I don't think that is what he was thinking. I think.

If the fridge has a fault to the frame and the cord has an EGC, the fault current has an path back to it's source and will be subtracted from the faulted conductor's current and the imbalance will trip the GFCI.

If there is no EGC, then the fault does not have a path back to it's source and will not cause an imbalance which would not trip the GFCI.

Just like your plug in tester. Pretend your plug in tester with the button pushed in is the fridge and the cord's ECG was missing. Would the GFCI's not behave exactly the same as stated in the OP's dillema?

 

[GoldDigger]

Unless a EGC is connected to the Neutral or Hot conductor on the load side of the GFCI (with a resistance that allows a total current of 4--6mA or more) it has no effect.

EGCs are not required for either the line or load sides of a GFCI. There are applications of GFCIs that require this independence.

The only harm from an absent EGC is the pushbutton plugin "GFCI testers" don't work.

On the contrary. If the fridge has leakage to its "grounded" metal and there is no separate ground bond provided by, say, a water line, then removing the EGC connection to the fridge will stop the leakage current (except small capacitive) until something or someone else supplies the return path.
It is also possible that the other GFCI receptacle would not trip if it is not providing an EGC for some reason. It would still trip from its own test button.

 

[GUNNING]

Hot box

Hot box

Did you see it trip, or does it trip only when someone is touching a sink and reaches over to open the refer (or something like that). That is a memory from my childhood, beforefore GFCIs. Got a "nice" shock, turned the plug around, no more shock. Today I would replace the refer (except I was 8 at the time).

I had a similar problem last year. The fridge is on rubber feet. When I plugged in the fridge I would lean on the side and it would trip. The frige case was hot and insulated from ground by the feet. Sometimes the water line or frost will make contact with an energized part like the light or ice maker or between the mollex connectors inside. Then the GFCI trips if you are lucky. Check with an ohm meter from metal case to ground prong or case to neutral. If you see continuity you have a hot fridge so to speak.